Light-Induced In Situ Formation of a Nonmetallic Plasmonic MoS₂/MoO_3–x Heterostructure with Efficient Charge Transfer for CO₂ Reduction and SERS Detection

Low-cost and abundant reserved nonmetallic plasmonic materials have been regarded as a promising substitute of noble metals for photocatalysis and surface-enhanced Raman scattering (SERS). In this paper, a MoS2/MoO3–x heterostructure was synthesized by light-induced in situ partial oxidation of MoS2 nanosheets, exhibiting strong surface plasmon resonance (SPR) in a vis–near-infrared (NIR) region. Continuously plasmon-induced hot electrons boost CO2 reduction to CO due to efficient photoelectron injection from MoS2 to MoO3–x. Under UV–vis–NIR irradiation, the CO generation rate reached 32.4 μmol g–1 h–1 with a selectivity of 94.1%, which was much higher than that of single MoS2 or MoO3–x. Furthermore, the plasmonic MoS2/MoO3–x heterostructure exhibits superior SERS performance for sensitive rhodamine 6G detection (10–9 M) with an enhancement factor of ∼106 because of the synergy between SPR and charge transfer effect. This work provides one novel mild synthetization of a plasmonic heterostructure and demonstrates its potential in plasmon-enhanced CO2 reduction and SERS detection.